I see that it's a 3-piece set, those two smaller pieces, are they attached to the back of the third row seats?

Yes, the two smaller pieces that go on the back of the rear seats are attached to the carpet with velcro. The mat set includes velcro strips for models that don't have carpet but it looks like some drilling (minor) is required. The mat has a good design that hinges to allow the rear seats to be folded up without having to remove the rear mat.

The mat set is nice, but is seems that this car is intended to be used with the middle row of seat upright at all times. I'd like to find a big rubber mat that I could slide forward when the middle seats are down; something that would protect the back of the seats as well as be stiff enough to bridge the cracks in between the seats. Even better if it could be folded up to protect the backs of the front seats.

How do you like it now that you've installed them? I regularly haul bags of soil, so I'm definitely looking for a cargo liner. I like that this one allows for the liners to be left on whether the back seat is up or down.

How do you like it now that you've installed them? I regularly haul bags of soil, so I'm definitely looking for a cargo liner. I like that this one allows for the liners to be left on whether the back seat is up or down.

Thanks

Overall it is ok. I think this is only custom fit rubber liner if you want the back seat up without removing the liner.

The liner has three big pieces and two of them sticks to the seat by velcro. Strangely the set comes with tape velcro that you are supposed to glue to the back seat and even make holes with drill, but I didn't find it is necessary since the default velcro is strong enough to hold the liner in-place.

The big bottom piece is not attached to top pieces and that makes the piece moving when you haul heavy objects in and out from the car, making small gap from top pieces, so you should not expect seamless coverage for your trunk. And also the removable cover for the seat lever is annoyance if you want it covered when laying flat because you need to remove it every time you make the back seat up. In the end, I am not using the lever cover anymore.

And the rubber material is not good at hiding dirt if you ever need to step your foot on it for hauling bags. Your footprint will remain very visible until washed with wet cloth.